Mordants have been extensively investigated for use in photography. In dye image transfer photography mobile dye is transferred imagewise to a mordant uniformly coated on a receiver, usually in a gelatin binder which is hardened to give structural integrity to the coating. The mordant immobilizes the dye to product a viewable image. A discussion of image dye mordanting in image transfer photography is provided in Research Disclosure, Vol. 151, November 1976, Item 15162. Research Disclosure is published by Kenneth Mason Publications, Ltd., Emsworth, Hampshire P010 7DD, England, Campbell et al U.S. Pat. No. 3,958,995 illustrates a crosslinked mordnt useful in diffusion transfer photography. Wagner et al U.K. Pat. No. 1,594,961 discloses avoiding gelatin hardening by providing hardening sites in the mordant. Helling U.S. Pat. No. 4,353,972 discloses mordants which reduce dye wandering in image transfer photography by reacting with latex polymer particles.
More recently interest has developed in photographically forming dye mordanting domains in the course of forming filters for electronic image sensors. Forming color filter arrays useful with semiconductor sensors has proven particularly challenging because of the small individual sensor areas, commonly less than 1.times.10.sup.-8 m.sup.2 in area, with areas of less than 1.times.10.sup.-10 m.sup.2 often being sought.
A common approach that has been taken is to blend a mordant of the same type used for image transfer photography with a negative-working photoresist. Imagewise exposure of the photoresist followed by development leaves hardened photoresist and occluded mordant in exposed areas. Hartman U.S. Pat. No. 4,315,978 is illustrative of this approach.
While this approach to mordant patterning has proven workable, the filters produced have exhibited limitations, as might be expected. The mordants themselves, being borrowed from image transfer photography, have no imaging capability. The photoresists, developed primarily for use as protective, usually transient layers in semiconductor fabrication, have exhibited a variety of limitations, including significant optical density (both as initially coated and on aging) and limited solution stability. Further, the combination of both mordant and photoresist molecules in a single layer can mitigate against achieving thinner layers of satisfactory dye imparted optical densities.
Toshiba Kokai No. 79246/1984, based on Application No. 189,081/1982, filed Oct. 29, 1982, discloses a resist composition for forming color filter elements containing 4-vinyl-N-methylpyridinium pendant groups. However, it is observed that repeating units containing these pendant groups are to be limited to 10 percent or less on a mole basis to avoid composition poor in photosensitivity and incapable of forming an aqueous solution.
Sanada el al, "New Deep UV Dyeable Negative Resist for CCD Micro Color Filter", SPIE, Vol. 631, Advances in Resist Technology and Processing III (1986), pp, 187-191, discloses for use in forming filter elements for charge control devices quaternary salt terminated acrylate-glycidyl methacrylate copolymers which are crosslinked by bisazides. One difficulty of the approach is that a separate compound, the bisazide, is relied upon for crosslinking. Variances in proportions of reactants will, of course, lead to non-uniformity of results. Another fundamental difficulty is the necessity of employing very short ultraviolet (hereinafter also referred to as UV) wavelengths for crosslinking. This excludes from use the most common pattern forming exposure equipment specifically developed for fabricating semiconductor devices.